The polymer matrix in current dental composites deforms rapidly and accumulates stresses during and immediately after exposure to the curing light. Stresses trapped in the resin matrix result in more susceptibility to damage and ultimate failure during function. The purpose of this research is to develop a biomimetic additive for methacrylate-based dental resins that will reduce or eliminate early damage to the resin matrix. We will develop and evaluate a series of peptides that will be terminated with methacrylate groups, yet provide a flexible and strong "shock absorber" for stiffer polymer chains as they solidify. Such an additive could substantially increase the life of composite restoratives and potentially expand the applications in which they are used. This approach has never before, to our knowledge, been tried. The inspiration is the way that nature builds biomaterials: flexible reinforcements (for fracture resistance and toughness) coupled to a hard mineral component (for durability and wear). The significance for internal reduction of shrinkage stress and fracture propagation is enormous. Our approach uses the same dimethacrylates used in commercial composites but adds a peptide linkage to reduce stress and fracture. This biomimetic approach offers additional advantages. We can design peptide sequences of various elements to achieve the necessary characteristics of the polymer and composite. This is the first time that this level of control has been available for modifying the qualities and performance characteristics of methacrylate-based composites. Designs might be customized for particular biological conditions and mechanical environments. The research route to these objectives includes chemical modeling, directed synthesis, reaction characterization, and physical/mechanical testing by clinically relevant methods. The research team in interdisciplinary, but tightly focused. K.V. Kilway contributes synthetic and physical organic expertise; A.J. Holder contributes experience in modeling polymer reactions; W.G. Gutheil provides the capability to synthesize the peptides; and R.L. Sakaguchi contributes materials testing expertise and equipment as well as significant experience and knowledge of practical problems in dental restorative materials. The work proposed here is the first step in developing a new class of new class of dental restoratives with much better performance and behavior. [unreadable] [unreadable] [unreadable]